The present invention generally relates to devices and methods to treat an eye of a patient, and more specifically to intraocular implants that provide extended release of a therapeutic agent to an eye in which the implant is placed to treat ocular hypertension, such as by reducing or at least maintaining intraocular pressure (IOP), and to methods of making and using such implants.
Ocular hypotensive agents are useful in the treatment of a number of various ocular hypertensive conditions, such as post-surgical and post-laser trabeculectomy ocular hypertensive episodes, glaucoma, and as presurgical adjuncts.
Glaucoma is a disease of the eye often characterized by increased intraocular pressure. On the basis of its etiology, glaucoma has been classified as primary or secondary. For example, primary glaucoma in adults (congenital glaucoma) may be either open-angle or acute or chronic angle-closure. Secondary glaucoma results from pre-existing ocular diseases such as uveitis, intraocular tumor or an enlarged cataract.
The increased intraocular tension in glaucoma is due to the obstruction of aqueous humor outflow. In chronic open-angle glaucoma, the anterior chamber and its anatomic structures appear essentially normal, but drainage of the aqueous humor is impeded. In acute or chronic angle-closure glaucoma, the anterior chamber is shallow, the filtration angle is narrowed, and the iris may obstruct the trabecular meshwork at the entrance of the canal of Schlemm. Dilation of the pupil may push the root of the iris forward against the angle, and may produce pupillary block and thus precipitate an acute attack. Eyes with narrow anterior chamber angles are predisposed to acute angle-closure glaucoma attacks of various degrees of severity.
Secondary glaucoma is caused by any interference with the flow of aqueous humor from the posterior chamber into the anterior chamber and subsequently, into the canal of Schlemm. Inflammatory disease of the anterior segment may prevent aqueous escape by causing complete posterior synechia in iris bombe and may plug the drainage channel with exudates. Other common causes are intraocular tumors, enlarged cataracts, central retinal vein occlusion, trauma to the eye, operative procedures and intraocular hemorrhage.
Reduction of intraocular pressure may help to prevent glaucoma or loss of vision due to glaucoma. Currently, eye drops containing therapeutically active agents for reducing intraocular pressure are given to many patients, who may take the drops one or more times a day to reduce elevated intraocular pressure associated with glaucoma.
It would be advantageous to provide eye implantable drug delivery systems, such as intraocular implants, and methods of using such systems, that are capable of releasing a therapeutic agent, such as a hypotensive (or IOP-lowering) agent, at a sustained or controlled rate for extended periods of time and in amounts with few or absent negative side effects to thereby reduce intraocular pressure in an eye of a patient, including but not limited to patients suffering from or at risk of developing glaucoma.